And yet, the price for a wifi-less device is about €100 less... There's only one store here that sells the device (with wifi) for €299 (which is including VAT). The rest is between €350 and €399.

Sorry, the 30 USD would be off the bulk sale. If only you knew how much the bulk sale price is and then the 100 Euro difference would somewhat make sense. Of course unfortunately, I cannot tell that number to the public.